JPH0522079B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a screw-type vacuum pump having a check valve in a flow path on the suction port side.

(Prior Art) Conventionally, as shown in FIG. 3, in a vacuum apparatus, a plurality of screw-type vacuum pumps 12 (in the illustrated example, three screw-type vacuum pumps 12) are connected in parallel to a common suction channel 11. Each branch channel 14 leading to the port 13
is provided with a check valve 16 for preventing the pump body 15 from reversing.

Here, the screw type pump main body 15 generally has a suction port 13 on one side, as shown in FIG.
A pair of female and male screw rotors 1 that mesh with each other are disposed in a casing 18 having a discharge port 17 on the other side.
9 is rotatably housed, and is formed so as to be rotationally driven in a fixed direction by a rotor shaft 20 on the side of the suction port 13 which is passed through to the outside of the casing 18, for example. As shown by the solid line arrow in the figure, this pump body 15 sucks in gas from the suction port 13 and discharges it from the discharge port 17. If there is a suction force in the direction opposite to the arrow, gas will flow in from the discharge port 17 in the direction of the dashed arrow, and the structure can rotate in the opposite direction.

Therefore, as shown in FIG.
If there is no check valve 16, if the pipe is a common pipe,
For example, if only the rightmost pump body 15 in the figure is stopped, the stopped pump body 15 will rotate in the opposite direction due to the suction force from the other two pump bodies 15 that are in operation, as shown by the broken line arrows. You end up doing it. If the stopped pump main body 15 rotates in the opposite direction, it will operate without lubricating oil being supplied to its bearings, synchronous gears, and other locations that require lubricating oil, resulting in damage to the device.

In order to prevent such a situation, the pump body 1
A check valve 16 is used to prevent reverse rotation of 5.

In the case of a commercially available check valve 16, as shown in FIG.
A valve body 23 having a gas circulation space 22 therein, and a valve body 2 provided so as to be able to come into close contact with this valve seat 21.
4, and a coil spring 25 that constantly biases the valve body 24 toward the valve seat so as to bring the valve body 24 into close contact with the valve seat 21. When suction force is applied from the suction port 13, that is, when suction force is applied from the x port side in the figure, the valve opens and gas flows from the y port to the x port as shown by the solid arrow. flowing,
Conversely, if suction force is applied from another pump main body 15, that is, if suction force is applied from the y port side,
The valve body 24 is in close contact with the valve seat 21, so that the valve is closed and gas backflow is prevented.

(Problems to be Solved by the Invention) In the vacuum pump 12 using the check valve 16 configured as described above, if the spring constant of the coil spring 25 is small, if the suction force is reversed and is generated from the y port side, the valve There is a time delay in closing the pump body 15, and reverse rotation of the pump body 15 cannot be completely prevented.

On the other hand, if the above spring constant is increased,
In a vacuum device, since the density of the inflowing gas is low, there is a problem in that the valve body 24 repeatedly collides with the valve seat 21, causing a hunting phenomenon in which the valve opens and closes.

The present invention has been made to address the above-mentioned conventional problems, and an object thereof is to provide a screw-type vacuum pump that can reliably and immediately open and close a check valve.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a pump main body having a pair of male and female screw rotors that mesh with each other, a suction port and a discharge port on both sides, and a rotational driving force of a prime mover. Passes through a speed increaser that increases speed and transmits it to the screw rotor, a casing of the speed increaser that also serves as an oil tank, a lubricating oil supply location in the pump body, the speed increaser, oil tank, oil pump, and oil cooler. In a screw-type vacuum pump equipped with an oil circulation flow path and a check valve provided in a flow path leading to a suction port of the pump body, the check valve is installed in a gas circulation space and a cylinder space that have a valve seat in the middle. is formed inside the valve body, and while keeping both spaces separated from each other via a sealing means, the partition part of both spaces is penetrated, and the gas circulation space side is connected to the valve seat in this space. A valve body is formed to be able to fit closely together, and is provided with a piston that partitions this space on the cylinder space side and forms an oil chamber on the gas circulation space side of this space and an atmosphere communication space on the opposite side, and this valve. and a spring means that constantly biases the body toward the valve seat so as to bring the body into close contact with the valve seat, and a bypass that communicates the oil chamber with the outlet side of the oil cooler and the oil tank via a three-way switching valve. Provide a flow path,
The flow path is formed so as to be switchable from the oil chamber to either the outlet side of the oil cooler or the oil tank.

(Function) By configuring the present invention as described above,
The check valve is opened by hydraulic pressure, and only when closing, a spring means is used.The spring constant of the spring means can be freely selected as appropriate, and the structure is such that the valve can be closed quickly and opened reliably. There is.

(Example) Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a screw-type vacuum pump 1 according to the present invention, which includes a screw-type pump main body 15 substantially the same as that shown in FIG. 4, an oil circulation passage 2, a check valve 3, and a bypass. 4, and the same parts as in FIG. 4 are given the same numbers.

Furthermore, FIG. 1 shows a portion of the pump main body 15 that is omitted from the drawing in FIG. gear 3
1. Rotational driving force from a prime mover (not shown) is transmitted to the screw rotor 19 via the large gear 32.

The oil circulation flow path 2 is connected from the oil reservoir 33 to the oil pump 3.
5. Consists of a flow path that passes through the oil cooler 36 to the lubricating oil supply points such as bearings, shaft seals, and synchronous gears in the pump 15, and then returns to the oil sump 33. It is designed to circulate.

On the other hand, in this embodiment, the check valve 3 is composed of a valve body 37, a valve body 38, and a coil spring 39.

Of these, the valve body 37 has inside thereof a gas circulation space 41 in which a valve seat 40 is provided in the intermediate portion, and a cylinder space 42, and a partition portion 43 is formed between the two.

The valve body 38 passes through the partition portion 43 via an O-ring 44 while keeping both spaces separated from each other. The gas circulation space side of the valve body 38 is formed so as to be in close contact with the valve seat 40, and this space is partitioned on the cylinder space 42 side, and an oil chamber 45 is connected to the gas circulation space side and communicated with the atmosphere on the opposite side. A piston 47 defining a space 46 is provided.

That is, oil from the oil reservoir 33 described below is introduced into the oil chamber 45, and an atmosphere communication hole 4 is provided on the side of the atmosphere communication space 46.
8, and both spaces are sealed by an O-ring 49 fitted around the piston 47.

The coil spring 39 is provided so as to constantly bias the valve body 38 in a direction to bring it into close contact with the valve seat 40.

Next, the bypass flow path 4 connects the oil chamber 45 to a,
It consists of a flow path that communicates with the outlet side of the oil cooler 36 and the oil sump section 33 via a three-way switching valve 50 having b and c ports, and is connected to either the outlet side of the oil cooler 36 from the oil chamber 45 or the oil sump section 33. The flow path is formed so as to be switchable to one direction.

When the b-c ports are in communication, the oil chamber 45 is in communication with the oil reservoir 33 which is at atmospheric pressure, and the oil in the oil chamber 45 is transferred to the oil reservoir 33.
The force of the coil spring 39 moves the valve body 38 to the left in FIG. 1, and the valve is closed.

On the other hand, when the a-b ports are in communication, the oil in the oil circulation flow path 2 is guided to the oil chamber 45, where the oil pressure is applied to the force of the coil spring 39, as shown in FIG. The valve element 38 is moved to the right in the figure, and the valve is in an open state.

In this way, the valve is opened using hydraulic pressure, and the force of the coil spring 39 when the valve is closed can be freely selected.

Next, the operation of the vacuum pump having the above configuration will be explained.

When the vacuum pump 1 is stopped, the oil pump 35 is stopped and the b-c ports of the three-way switching valve 50 are brought into communication. As a result, the oil reservoir 3 in the oil chamber 45
3, and the valve body 38 is pulled out by the force of the coil spring 39.
is in close contact with the valve seat 40 and the valve is closed.

On the other hand, when the vacuum pump 1 is operating, the oil pump 35
is operated to bring the a and b ports of the three-way switching valve 50 into communication. As a result, hydraulic pressure is generated in the oil chamber 45, the valve body 38 moves to the right, and the valve opens.
A gas flow path is secured.

(Effects of the Invention) As is clear from the above description, according to the present invention, a check valve includes a valve body having a gas circulation space and a cylinder space formed therein, which have a valve seat in the middle, and a sealing means. While keeping the two spaces separated from each other through the spacer, the partition between the two spaces is penetrated so that the gas circulation space side can be brought into close contact with the valve seat in this space, and the cylinder space side is provided with this space. A valve body is provided with a piston that partitions a space and forms an oil chamber on the gas circulation space side of the space and an atmosphere communication space on the opposite side, and the valve seat is arranged so that the valve body is in close contact with the valve seat. and a bypass flow path that communicates the oil chamber with the outlet side of the oil cooler and the oil tank via a three-way switching valve, so that the oil chamber can be connected to the oil cooler from the oil chamber. The flow path can be switched to either the outlet side of the oil tank or the oil tank.

For this reason, it is possible to freely select a spring means that has the necessary spring constant to bring the valve body into close contact with the valve seat reliably and quickly, preventing gas backflow, and opening the valve reliably with hydraulic pressure to prevent the hunting phenomenon. This has the effect that a gas flow path can be secured without causing any problems.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of a screw-type vacuum pump according to the present invention, Fig. 2 is a schematic partial sectional view of the check valve part during operation as shown in Fig. 1, and Fig. 3 is a schematic cross-sectional view of a screw-type vacuum pump according to the present invention. FIG. 4 is a sectional view of the pump body of a screw-type vacuum pump, and FIG. 5 is a sectional view of a conventional check valve. DESCRIPTION OF SYMBOLS 1...Vacuum pump, 2...Oil circulation channel, 3...Check valve, 4...Bypass channel, 13...Suction port, 15...Pump body, 17...Discharge port, 19...Screw rotor, 35...Oil pump, 36... Oil cooler, 37... Valve body, 38... Valve body, 39... Coil spring, 40... Valve seat, 41... Gas circulation space, 42... Cylinder space,
43... Partition portion, 45... Oil chamber, 46... Atmospheric communication space, 47... Piston, 50... Three-way switching valve.

Claims (1)

[Claims] 1. A pump body having a pair of male and female screw rotors that mesh with each other, a suction port and a discharge port on both sides, a speed increaser that increases the rotational driving force of the prime mover and transmits it to the screw rotor, and a speed increaser that also serves as an oil tank. A non-return check installed in the speed gear casing, the lubricating oil supply location in the pump body, the oil circulation flow path that passes through the speed increaser, oil tank, oil pump, and oil cooler, and the flow path leading to the pump body suction port. In the screw-type vacuum pump equipped with a valve, the check valve is connected to a valve body in which a gas circulation space and a cylinder space having a valve seat in the middle are formed, and the two spaces are connected to each other through a sealing means. While keeping the space in a slightly disconnected state, the partition portion between both spaces is penetrated so that the gas distribution space side can be brought into close contact with the valve seat in this space, and the inside of this space is partitioned off on the cylinder space side. a valve body with a piston that forms an oil chamber on the gas circulation space side and an atmosphere communication space on the opposite side;
The valve body is formed of a spring means that constantly biases the valve body in the direction of the valve seat so as to tightly contact the valve seat, and the oil chamber is communicated with the outlet side of the oil cooler and the oil tank through a three-way switching valve. 1. A screw-type vacuum pump characterized in that a bypass flow path is provided so that the flow path can be switched from an oil chamber to either an outlet side of the oil cooler or an oil tank.